For a binary tree to be a binary search tree (BST), the data of all the nodes in the left sub-tree of the root node should be less than or equals to the data of the root. The data of all the nodes in the right subtree of the root node should be greater than the data of the root.
Here is an example picture of binary search tree (BST):
BTS Node:
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package com.java2novice.ds; public class BstNode { private BstNode left; private BstNode right; private Integer data; public BstNode(Integer data) { this.data = data; } public BstNode getLeft() { return left; } public void setLeft(BstNode left) { this.left = left; } public BstNode getRight() { return right; } public void setRight(BstNode right) { this.right = right; } public Integer getData() { return data; } } |
Implement Binary Search Tree (BST) in Java
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package com.java2novice.ds; public class BinarySearchTreeImpl { private BstNode root; public boolean isEmpty() { return (this.root == null); } public void insert(Integer data) { System.out.print("[input: "+data+"]"); if(root == null) { this.root = new BstNode(data); System.out.println(" -> inserted: "+data); return; } insertNode(this.root, data); System.out.print(" -> inserted: "+data); System.out.println(); } private BstNode insertNode(BstNode root, Integer data) { BstNode tmpNode = null; System.out.print(" ->"+root.getData()); if(root.getData() >= data) { System.out.print(" [L]"); if(root.getLeft() == null) { root.setLeft(new BstNode(data)); return root.getLeft(); } else { tmpNode = root.getLeft(); } } else { System.out.print(" [R]"); if(root.getRight() == null) { root.setRight(new BstNode(data)); return root.getRight(); } else { tmpNode = root.getRight(); } } return insertNode(tmpNode, data); } public static void main(String a[]) { BinarySearchTreeImpl bst = new BinarySearchTreeImpl(); bst.insert(10); bst.insert(20); bst.insert(21); bst.insert(8); bst.insert(6); bst.insert(16); bst.insert(23); } } |
Find min and max value from Binary Search Tree (BST) in Java
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package com.java2novice.ds; public class BinarySearchTreeImpl { private BstNode root; public boolean isEmpty() { return (this.root == null); } public void insert(Integer data) { System.out.print("[input: "+data+"]"); if(root == null) { this.root = new BstNode(data); System.out.println(" -> inserted: "+data); return; } insertNode(this.root, data); System.out.print(" -> inserted: "+data); System.out.println(); } private BstNode insertNode(BstNode root, Integer data) { BstNode tmpNode = null; System.out.print(" ->"+root.getData()); if(root.getData() >= data) { System.out.print(" [L]"); if(root.getLeft() == null) { root.setLeft(new BstNode(data)); return root.getLeft(); } else { tmpNode = root.getLeft(); } } else { System.out.print(" [R]"); if(root.getRight() == null) { root.setRight(new BstNode(data)); return root.getRight(); } else { tmpNode = root.getRight(); } } return insertNode(tmpNode, data); } public Integer findMinValue() { return minValue(this.root); } public Integer findMaxValue() { return maxValue(this.root); } private Integer minValue(BstNode node) { if(node.getLeft() != null) { return minValue(node.getLeft()); } return node.getData(); } private Integer maxValue(BstNode node) { if(node.getRight() != null) { return maxValue(node.getRight()); } return node.getData(); } public static void main(String a[]) { BinarySearchTreeImpl bst = new BinarySearchTreeImpl(); bst.insert(10); bst.insert(20); bst.insert(21); bst.insert(8); bst.insert(6); bst.insert(16); bst.insert(23); bst.insert(2); System.out.println("-------------------"); System.out.println("Min value: "+bst.findMinValue()); System.out.println("Max value: "+bst.findMaxValue()); } } |
Find height of a Binary Search Tree (BST) in Java
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package com.java2novice.ds; public class BinarySearchTreeImpl { private BstNode root; public boolean isEmpty() { return (this.root == null); } public void insert(Integer data) { System.out.print("[input: "+data+"]"); if(root == null) { this.root = new BstNode(data); System.out.println(" -> inserted: "+data); return; } insertNode(this.root, data); System.out.print(" -> inserted: "+data); System.out.println(); } private BstNode insertNode(BstNode root, Integer data) { BstNode tmpNode = null; System.out.print(" ->"+root.getData()); if(root.getData() >= data) { System.out.print(" [L]"); if(root.getLeft() == null) { root.setLeft(new BstNode(data)); return root.getLeft(); } else { tmpNode = root.getLeft(); } } else { System.out.print(" [R]"); if(root.getRight() == null) { root.setRight(new BstNode(data)); return root.getRight(); } else { tmpNode = root.getRight(); } } return insertNode(tmpNode, data); } public Integer findHeight(){ return getNodeHeight(this.root); } private Integer getNodeHeight(BstNode node) { if(node == null) { return -1; } return Math.max(getNodeHeight(node.getLeft()), getNodeHeight(node.getRight()))+1; } public static void main(String a[]) { BinarySearchTreeImpl bst = new BinarySearchTreeImpl(); bst.insert(10); bst.insert(20); bst.insert(21); bst.insert(8); bst.insert(6); bst.insert(16); bst.insert(23); bst.insert(2); System.out.println("-------------------"); System.out.println("Height of the tree: "+bst.findHeight()); } } |
Implement Binary Search Tree (BST) Level order traversal (breadth first) in Java
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package com.java2novice.ds; import java.util.LinkedList; import java.util.Queue; public class BinarySearchTreeImpl { private BstNode root; public boolean isEmpty() { return (this.root == null); } public void insert(Integer data) { System.out.print("[input: "+data+"]"); if(root == null) { this.root = new BstNode(data); System.out.println(" -> inserted: "+data); return; } insertNode(this.root, data); System.out.print(" -> inserted: "+data); System.out.println(); } private BstNode insertNode(BstNode root, Integer data) { BstNode tmpNode = null; System.out.print(" ->"+root.getData()); if(root.getData() >= data) { System.out.print(" [L]"); if(root.getLeft() == null) { root.setLeft(new BstNode(data)); return root.getLeft(); } else { tmpNode = root.getLeft(); } } else { System.out.print(" [R]"); if(root.getRight() == null) { root.setRight(new BstNode(data)); return root.getRight(); } else { tmpNode = root.getRight(); } } return insertNode(tmpNode, data); } public void levelOrderTraversal() { Queue<BstNode> discovedNodeQueue = new LinkedList<>(); if(this.root == null) { System.out.println("The tree is empty."); return; } discovedNodeQueue.add(this.root); while (!discovedNodeQueue.isEmpty()) { BstNode tmpNode = discovedNodeQueue.remove(); if(tmpNode.getLeft() != null) { discovedNodeQueue.add(tmpNode.getLeft()); } if(tmpNode.getRight() != null) { discovedNodeQueue.add(tmpNode.getRight()); } System.out.print(tmpNode.getData()+" "); } } public static void main(String a[]) { BinarySearchTreeImpl bst = new BinarySearchTreeImpl(); bst.insert(8); bst.insert(10); bst.insert(14); bst.insert(3); bst.insert(6); bst.insert(7); bst.insert(1); bst.insert(4); bst.insert(13); System.out.println("-------------------"); System.out.println("Level order traversal"); bst.levelOrderTraversal(); } } |
Implement Binary Search Tree (BST) pre-order traversal (depth first) in Java:
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package com.java2novice.ds; import java.util.LinkedList; import java.util.Queue; public class BinarySearchTreeImpl { private BstNode root; public boolean isEmpty() { return (this.root == null); } public void insert(Integer data) { System.out.print("[input: "+data+"]"); if(root == null) { this.root = new BstNode(data); System.out.println(" -> inserted: "+data); return; } insertNode(this.root, data); System.out.print(" -> inserted: "+data); System.out.println(); } private BstNode insertNode(BstNode root, Integer data) { BstNode tmpNode = null; System.out.print(" ->"+root.getData()); if(root.getData() >= data) { System.out.print(" [L]"); if(root.getLeft() == null) { root.setLeft(new BstNode(data)); return root.getLeft(); } else { tmpNode = root.getLeft(); } } else { System.out.print(" [R]"); if(root.getRight() == null) { root.setRight(new BstNode(data)); return root.getRight(); } else { tmpNode = root.getRight(); } } return insertNode(tmpNode, data); } public void preOrderTraversal() { doPreOrder(this.root); } private void doPreOrder(BstNode root) { if(root == null) return; System.out.print(root.getData()+" "); doPreOrder(root.getLeft()); doPreOrder(root.getRight()); } public static void main(String a[]) { BinarySearchTreeImpl bst = new BinarySearchTreeImpl(); bst.insert(8); bst.insert(10); bst.insert(14); bst.insert(3); bst.insert(6); bst.insert(7); bst.insert(1); bst.insert(4); bst.insert(13); System.out.println("\n-------------------"); System.out.println("Pre Order Traversal"); bst.preOrderTraversal(); } } |
Implement Binary Search Tree (BST) in-order traversal (depth first) in Java
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package com.java2novice.ds; import java.util.LinkedList; import java.util.Queue; public class BinarySearchTreeImpl { private BstNode root; public boolean isEmpty() { return (this.root == null); } public void insert(Integer data) { System.out.print("[input: "+data+"]"); if(root == null) { this.root = new BstNode(data); System.out.println(" -> inserted: "+data); return; } insertNode(this.root, data); System.out.print(" -> inserted: "+data); System.out.println(); } private BstNode insertNode(BstNode root, Integer data) { BstNode tmpNode = null; System.out.print(" ->"+root.getData()); if(root.getData() >= data) { System.out.print(" [L]"); if(root.getLeft() == null) { root.setLeft(new BstNode(data)); return root.getLeft(); } else { tmpNode = root.getLeft(); } } else { System.out.print(" [R]"); if(root.getRight() == null) { root.setRight(new BstNode(data)); return root.getRight(); } else { tmpNode = root.getRight(); } } return insertNode(tmpNode, data); } public void inOrderTraversal() { doInOrder(this.root); } private void doInOrder(BstNode root) { if(root == null) return; doInOrder(root.getLeft()); System.out.print(root.getData()+" "); doInOrder(root.getRight()); } public static void main(String a[]) { BinarySearchTreeImpl bst = new BinarySearchTreeImpl(); bst.insert(8); bst.insert(10); bst.insert(14); bst.insert(3); bst.insert(6); bst.insert(7); bst.insert(1); bst.insert(4); bst.insert(13); System.out.println("\n-------------------"); System.out.println("In Order Traversal"); bst.inOrderTraversal(); } } |
Implement Binary Search Tree (BST) post-order traversal (depth first) in Java
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package com.java2novice.ds; import java.util.LinkedList; import java.util.Queue; public class BinarySearchTreeImpl { private BstNode root; public boolean isEmpty() { return (this.root == null); } public void insert(Integer data) { System.out.print("[input: "+data+"]"); if(root == null) { this.root = new BstNode(data); System.out.println(" -> inserted: "+data); return; } insertNode(this.root, data); System.out.print(" -> inserted: "+data); System.out.println(); } private BstNode insertNode(BstNode root, Integer data) { BstNode tmpNode = null; System.out.print(" ->"+root.getData()); if(root.getData() >= data) { System.out.print(" [L]"); if(root.getLeft() == null) { root.setLeft(new BstNode(data)); return root.getLeft(); } else { tmpNode = root.getLeft(); } } else { System.out.print(" [R]"); if(root.getRight() == null) { root.setRight(new BstNode(data)); return root.getRight(); } else { tmpNode = root.getRight(); } } return insertNode(tmpNode, data); } public void postOrderTraversal() { doPostOrder(this.root); } private void doPostOrder(BstNode root) { if(root == null) return; doPostOrder(root.getLeft()); doPostOrder(root.getRight()); System.out.print(root.getData()+" "); } public static void main(String a[]) { BinarySearchTreeImpl bst = new BinarySearchTreeImpl(); bst.insert(8); bst.insert(10); bst.insert(14); bst.insert(3); bst.insert(6); bst.insert(7); bst.insert(1); bst.insert(4); bst.insert(13); System.out.println("\n-------------------"); System.out.println("Post Order Traversal"); bst.postOrderTraversal(); } } |
Delete a node from Binary Search Tree (BST) in Java
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package com.java2novice.ds; import java.util.LinkedList; import java.util.Queue; public class BinarySearchTreeImpl { private BstNode root; public boolean isEmpty() { return (this.root == null); } public BstNode getRoot() { return this.root; } public void insert(Integer data) { System.out.print("[input: "+data+"]"); if(root == null) { this.root = new BstNode(data); System.out.println(" -> inserted: "+data); return; } insertNode(this.root, data); System.out.print(" -> inserted: "+data); System.out.println(); } private BstNode insertNode(BstNode root, Integer data) { BstNode tmpNode = null; System.out.print(" ->"+root.getData()); if(root.getData() >= data) { System.out.print(" [L]"); if(root.getLeft() == null) { root.setLeft(new BstNode(data)); return root.getLeft(); } else { tmpNode = root.getLeft(); } } else { System.out.print(" [R]"); if(root.getRight() == null) { root.setRight(new BstNode(data)); return root.getRight(); } else { tmpNode = root.getRight(); } } return insertNode(tmpNode, data); } public void delete(Integer data) { deleteNode(this.root, data); } private BstNode deleteNode(BstNode root, Integer data) { if(root == null) return root; if(data < root.getData()) { root.setLeft(deleteNode(root.getLeft(), data)); } else if(data > root.getData()) { root.setRight(deleteNode(root.getRight(), data)); } else { // node with no leaf nodes if(root.getLeft() == null && root.getRight() == null) { System.out.println("deleting "+data); return null; } else if(root.getLeft() == null) { // node with one node (no left node) System.out.println("deleting "+data); return root.getRight(); } else if(root.getRight() == null) { // node with one node (no right node) System.out.println("deleting "+data); return root.getLeft(); } else { // nodes with two nodes // search for min number in right sub tree Integer minValue = minValue(root.getRight()); root.setData(minValue); root.setRight(deleteNode(root.getRight(), minValue)); System.out.println("deleting "+data); } } return root; } private Integer minValue(BstNode node) { if(node.getLeft() != null) { return minValue(node.getLeft()); } return node.getData(); } public void inOrderTraversal() { doInOrder(this.root); } private void doInOrder(BstNode root) { if(root == null) return; doInOrder(root.getLeft()); System.out.print(root.getData()+" "); doInOrder(root.getRight()); } public static void main(String a[]) { BinarySearchTreeImpl bst = new BinarySearchTreeImpl(); bst.insert(8); bst.insert(10); bst.insert(14); bst.insert(3); bst.insert(6); bst.insert(7); bst.insert(1); bst.insert(4); bst.insert(13); System.out.println("-------------------"); System.out.println("In Order Traversal"); bst.inOrderTraversal(); System.out.println(); bst.delete(13); bst.inOrderTraversal(); System.out.println(); bst.delete(14); bst.inOrderTraversal(); } } |
